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It is shown in this ‘Part 2’ that heptaleno[1,2-c]furans 1 react thermally in a Diels–Alder-type [4+2] cycloaddition at the furan ring with vinylene carbonate (VC), phenylsulfonylallene (PSA), α-(acetyloxy)acrylonitrile (AAN), and (1Z)-1,2-bis(phenylsulfonyl)ethene (ZSE) to yield the corresponding 1,4-epoxybenzo[d]heptalenes (cf. Schemes 4;1, 5, 6, and 8). The thermal reaction of 1a and 1b with VC at 130° and 150°, respectively, leads mainly to the 2,3-endo-cyclocarbonates 2,3-endo-2a and -2b and in minor amounts to the 2,3-exo-cyclocarbonates 2,3-exo-2a and -2b. In some cases, the (P*)- and (M*)-configured epimers were isolated and characterized (Scheme 4;1). Base-catalyzed cleavage of 2,3-endo-2 gave the corresponding 2,3-diols 3, which were further transformed via reductive cleavage of their dimesylates 4 into the benzo[a]heptalenes 5a and 5b, respectively (Scheme 4;2). In another reaction sequence, the 2,3-diols 3 were converted into their cyclic carbonothioates 6, which on treatment with (EtO)3P gave the deoxygenated 1,4-dihydro-1,4-epoxybenzo[d]heptalenes 7. These were rearranged by acid catalysis into the benzo[a]heptalen-4-ols 8a and 8b, respectively (Scheme 4;2). Cyclocarbonate 2,3-endo-2b reacted with lithium diisopropylamide (LDA) at −70° under regioselective ring opening to the 3-hydroxy-substituted benzo[d]heptalen-2-yl carbamate 2,3-endo-9b (Scheme 4;3). The latter was O-methylated to 2,3-endo-(P*)-10b. The further way, to get finally the benzo[a]heptalene 13b with MeO groups in 1,2,3-position, could not be realized due to the fact that we found no way to cleave the carbamate group of 2,3-endo-(P*)-10b without touching its 1,4-epoxy bridge (Scheme 4;3).The reaction of 1a with PSA in toluene at 120° was successful, in a way that we found regioisomeric as well as epimeric cycloadducts (Scheme 4;5). Unfortunately, the attempts to rearrange the products under strong-base catalysis as it had been shown successfully with other furan–PSA adducts were unsuccessful (Scheme 4;4).The thermal cycloaddition reaction of 1a and 1b with AAN yielded again regioisomeric and epimeric adducts, which could easily be transformed into the corresponding 2- and 3-oxo products (Scheme 4;6). Only the latter ones could be rearranged with Ac2O/H2SO4 into the corresponding benzo[a]heptalene-3,4-diol diacetates 20a and 20b, respectively, or with trimethylsilyl trifluoromethanesulfonate (TfOSiMe3/Et3N), followed by treatment with NH4Cl/H2O, into the corresponding benzo[a]heptalen-3,4-diols 21a and 21b (Scheme 4;7).The thermal cycloaddition reaction of 1 with ZSE in toluene gave the cycloadducts 2,3-exo-22a and -22b as well as 2-exo,3-endo-22c in high yields (Scheme 8). All three adducts eliminated, by treatment with base, benzenesulfinic acid and yielded the corresponding 3-(phenylsulfonyl)-1,4-epoxybenzo[d]heptalenes 25. The latter turned out to be excellent Michael acceptors for H2O2 in basic media (Scheme 4;9). The Michael adducts lost H2O on treatment with Ac2O in pyridine and gave the 3-(phenylsulfonyl)benzo[d]heptalen-2-ones 28a and 3-exo-28b, respectively. Rearrangement of these compounds in the presence of Ac2O/AcONa lead to the formation of the corresponding 3-(phenylsulfonyl)benzo[a]heptalene-1,2-diol diacetates 30a and 30b, which on treatment with MeONa/MeI gave the corresponding MeO-substituted compounds 31a and 31b. The reductive elimination of the PhSO2 group led finally to the 1,2-dimethoxybenzo[a]heptalenes 32a and 32b. Deprotonation experiments of 32a with t-BuLi/N,N,N′,N′-tetramethylethane-1,2-diamine (tmeda) and quenching with D2O showed that the most acid C—H bond is H—C(3) (Scheme 4;9).Some of the new structures were established by X-ray crystal-diffraction analyses (cf. Figs. 4;1, 3, 4, and 5). Moreover, nine of the new benzo[a]heptalenes were resolved on an anal. Chiralcel OD-H column, and their CD spectra were measured (cf. Figs. 4;8 and 9). As a result, the 1,2-dimethoxybenzo[a]heptalenes 32a and 32b showed unexpectedly new Cotton-effect bands just below 300 4;nm, which were assigned to chiral exciton coupling between the heptalene and benzo part of the structurally highly twisted compounds. The PhSO2-substituted benzo[a]heptalenes 30b and 31b showed, in addition, a further pair of Cotton-effect bands in the range of 275–245 4;nm, due to chiral exciton coupling of the benzo[a]heptalene chromophore and the phenylsulfonyl chromophore (cf. Fig. 4;10). [ABSTRACT FROM AUTHOR]